In Exercises answer the given questions about the indicated examples of this section.

In Example 2, if the blade starts at an angle of −45°, what is the equation relating d and t as 

(a) A sine function? 

(b) A cosine function?

Data from Example 2

A windmill is used to pump water. The radius of the blade is 2.5 m, and it is moving with constant angular velocity. If the vertical displacement of the end of the blade is timed from the point it is at an angle of 45°(π/4 rad) from the horizontal [see Fig. 10.35(a)], the displacement d is given by

If the blade makes an angle of 90°(π/2 rad) when t = 0 [see Fig. 10.35(b)], the displacement d is given by

If timing started at the first maximum for the displacement, the resulting curve for the displacement would be that of the cosine function.

d=2.5 sin ut + 77 4.